Syntax highlighting

使用 highlight.js 给代码片断添加语法高亮, 并设置更优雅的字体
当前为 2019-10-16 提交的版本，查看最新版本。
换行
// ==UserScript==
// @name         Syntax highlighting
// @namespace    http://tampermonkey.net/
// @version      0.1.2
// @description  使用 highlight.js 给代码片断添加语法高亮, 并设置更优雅的字体
// @author       floatsyi
// @license      MIT
// @require      https://cdn.bootcss.com/highlight.js/9.15.10/highlight.min.js
// @require      https://cdn.bootcss.com/fontfaceobserver/2.1.0/fontfaceobserver.js
// @match             *://*/*
// @grant GM_addStyle
// @grant        GM_setValue
// @grant        GM_getValue
// @grant unsafeWindow
// ==/UserScript==
//  https://www.bootcdn.cn/highlight.js/
// console.log(unsafeWindow.FontFaceObserver)
const envDetection = [unsafeWindow.Prism, unsafeWindow.hljs]
if (envDetection.some(item => !!item)) return false

const themes = [
  'atom-one-dark',
  'brown-paper',
  'color-brewer',
  'docco',
  'darkula'
]
let currentTheme = themes[0]
const fonts = ['BioRhyme', 'Fira Code', 'Lato']
let currentFont = fonts[1]

const backgroundColor = '#272c34'

const fetchStyleText = url =>
  fetch(url, {
    headers: {
      'Content-Type': 'text/plain'
    }
  }).then(function (response) {
    return response.text()
  })

const setStyle = () => {
  const themeStyle = GM_getValue(currentTheme)

  if (themeStyle) {
    GM_addStyle(themeStyle)
  } else {
    const themeUrl = `https://cdn.bootcss.com/highlight.js/9.15.10/styles/${currentTheme}.min.css`

    fetchStyleText(themeUrl).then(function (style) {
      GM_addStyle(style)
      GM_setValue(currentTheme, style)
    })
  }

  const fontStyle = GM_getValue(currentFont)
  if (fontStyle) {
    GM_addStyle(fontStyle)
  } else {
    const fontUrl = `https://fonts.loli.net/css?family=${currentFont}`

    fetchStyleText(fontUrl).then(function (style) {
      GM_addStyle(style)
      GM_setValue(currentFont, style)
    })
  }
}

const setFont = () => {
  const font = new window.FontFaceObserver(currentFont)
  font.load().then(
    function () {
      console.log('Font is available')
      for (const pre of Array.from(document.querySelectorAll('pre'))) {
        const code = pre.querySelector('code')
        window.hljs.highlightBlock(code)
        code.style.fontFamily = currentFont
      }
    },
    function () {
      console.log('Font is not available')
    }
  )
}

setStyle()
setFont()

console.log('highlight runing')